Function of human amniotic mesenchymal stem cell exosomes in repairing submandibular gland epithelial cells after radiation injury in SD rats

• Both normoxic and hypoxic preconditioned human amniotic mesenchymal stem cell exosomes significantly improved the proliferation of radiation-injured submandibular gland epithelial cells. • Treatment with exosomes increased α-amylase secretion and aquaporin 5 mRNA expression in radiation-injured cells, indicating functional recovery. • Hypoxic preconditioning of exosomes did not confer a statistically significant advantage over normoxic exosomes in repairing radiation damage. • Exosomes derived from human amniotic mesenchymal stem cells may serve as a potential cell-free therapy for radiation-induced salivary gland injury.